A non invasive blood pressure measuring apparatus and a measuring method thereof. A main body (1) is provided with a microprocessor connected with a pressure sensor. A pressurized cuff (2) is a balloon cuff with a gas tube which is connected with the pressure sensor and fastened to a body portion at which the artery blood flow of a subject can be blocked completely after balloon inflation. The pressurized cuff (2) is provided with a pulse wave detector (3) fixed at a downstream portion of the pressurized cuff (2) according to the artery blood flow direction. The microprocessor performs a real time process to several pulse wave amplitudes which are detected by the pulse wave detector (3) and increasing slowly from zero and the corresponding pressures of the pressurized cuff to determine a systolic blood pressure and also the microprocessor performs a real time process to several pulse delay periods which are the delay periods between the pulse waves and the corresponding pressure alternative signals and from variable to relatively constant and the corresponding pressures of the pressurized cuff to determine a diastolic blood pressure. Possible and inevitable errors caused by discontinuity of heart beats can be avoid by a conversion from discontinuous events to a continuous measurement. The systolic blood pressure and the diastolic blood pressure of blood pressure can be measured accurately and non invasively.
